As and Epitaxial-Growth MnSi Thin Films - OPUS Würzburg

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80 6. Epitaxial Growth of MnSi Thin Films
Chapter 7 Magnetotransport with H ‖ [111] In this chapter, results of magnetotransport measurements with the applied field directed parallel to the [111] hard axis plane are discussed. The current issue of the Skyrmion lattice stabilization with out-of-plane fields and its topological contribution to the Hall effect are topical to the current developments in the study of MnSi and are central to the discussion presented here. 7.1 Hall Measurements Hall bars from 12 and 20-nm MnSi thin film layers were measured in an out-of-plane magnetic field ranging from 3T to 12 T using a liquid N 2 -shield He cryostat connected to a PS Oxford magnetic power supply, sweeping the field at both directions. Multiple Hall bars oriented along different crystalline directions are fabricated. (See Table 6.2) Simultaneous AC measurements of both the magnetoresistance and the Hall voltage using standard six-terminal configuration are all performed using EG&G Princeton Applied Research Model 124 analog lock-in amplifiers at 13Hz. Shown in Figure 7.1 are representative MR measurements on the 12 nm layer with currents along different crystal directions. The large negative magnetoresistance is consistent with observation of giant negative magnetoresistance in MnGe samples with the suppression of spin fluctuations and increased magnetic ordering along the field.[Li 07] The longitudinal magnetoresistance measurements show no preferred crystal direction for the current, which shows that the MnSi[111] is a magnetic hard axis separate from the in-plane anisotropies, consistent with out-of-plane SQUID results.(Figure 6.4) However, we measure a hysteresis between consecutive sweeps of the applied field, shown in Figure 7.2. This poses a problem inthe subsequent symmetrization calculations since we actually symmetrize on H, not on B = µ (H + M). 81
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Characterization of Novel Magnetic
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Contents Zusammenfassung 4 Summary
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Zusammenfassung Um einerseits ein f
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Zusammenfassung 3 auf die anomale t
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Summary The study of magnetic phase
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Summary 7 bandstructure affecting t
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Chapter 1 Introduction Spin electro
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11 states in the MnSi. Chapter 9 fi
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Chapter 2 Diluted Ferromagnetic Sem
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2.1. Basic properties of (Ga,Mn)As
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2.3. Electrical Control of Magnetiz
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2.4. (Ga, Mn)As and the Metal-Insul
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2.4. (Ga, Mn)As and the Metal-Insul
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2.5. Summary 23 2.5 Summary A brief
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Chapter 3 Electric Control of Magne
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3.2. Electrical control of magnetiz
Page 33 and 34: 3.2. Electrical control of magnetiz
Page 45 and 46: 3.3. Reproducible Conductance Fluct
Page 47 and 48: 3.4. Summary 43 changed significant
Page 49 and 50: Chapter 4 Epitaxial lift-off of (Ga
Page 51 and 52: 4.2. Test Barrier Material 47 Fig.
Page 53 and 54: 4.4. Magnetotransport in ELO-proces
Page 55 and 56: 4.4. Magnetotransport in ELO-proces
Page 57 and 58: 4.5. Electrical gating of ELO-proce
Page 59 and 60: Chapter 5 Basic properties of Ferro
Page 61 and 62: 5.1. Bulk properties of MnSi 57 (a)
Page 63 and 64: 5.2. Expitaxially-grown MnSi Thin F
Page 65 and 66: 5.2. Expitaxially-grown MnSi Thin F
Page 67 and 68: 5.3. Skyrmions, Chirality and Magne
Page 69 and 70: 5.3. Skyrmions, Chirality and Magne
Page 71 and 72: 5.4. Summary 67 tions. MnSi provide
Page 73 and 74: Chapter 6 Epitaxial Growth of MnSi
Page 75 and 76: 6.2. Material Characterization 71 F
Page 77 and 78: 6.2. Material Characterization 73 M
Page 79 and 80: 6.3. Device Fabrication 75 Fig. 6.5
Page 81 and 82: 6.4. Temperature-dependent measurem
Page 83: 6.5. Summary 79 expected for the he
Page 87 and 88: 7.1. Hall Measurements 83 0 J || [-
Page 89 and 90: 7.1. Hall Measurements 85 0.40 R xy
Page 91 and 92: 7.1. Hall Measurements 87 is two or
Page 93 and 94: 7.1. Hall Measurements 89 6 J || [1
Page 95 and 96: 7.1. Hall Measurements 91 0.02 0.00
Page 97 and 98: 7.1. Hall Measurements 93 0.100 -55
Page 99 and 100: 7.1. Hall Measurements 95 0.15 R xy
Page 101 and 102: 7.1. Hall Measurements 97 Magnetore
Page 103 and 104: 7.2. Summary 99 T c . The sign of t
Page 105 and 106: Chapter 8 Magnetotransport with In-
Page 107 and 108: 8.1. Magnetotransport Measurements
Page 119 and 120: 8.2. Summary 115 8.2 Summary Low ma
Page 121 and 122: Chapter 9 Conclusions & Outlook In
Page 123 and 124: Appendix A Fabrication of Four-Term
Page 125 and 126: A.2. Optimized final process 121 Fi
Page 127 and 128: A.2. Optimized final process 123 95
Page 129 and 130: Appendix B Epitaxial lift-off techn
Page 131 and 132: 127 Evap 2 Wire Rinse in water 1min
Page 133 and 134: Bibliography [Abra 96] E. Abrahams
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131 [Edmo 03] K. Edmonds. Journal o
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133 [Ishi 77] Y. Ishikawa, G. Shira
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135 [Mudu 05] P. K. Muduli, K.-J. F
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137 [Rich 10] A. Richardella, P. Ro
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139 [Vila 07] L. Vila, R. Giraud, L
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Acknowledgements First ofall I woul
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As and Epitaxial-Growth MnSi Thin Films - OPUS Würzburg

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